Silicon dioxide-cerium dioxide particles, preparation method thereof and application of ionic liquid

Abstract

The invention discloses silicon dioxide-cerium dioxide particles, a preparation method thereof and application of ionic liquid. The preparation method comprises the following steps: (1) adding a cerium salt aqueous solution into a first mixture containing silicon dioxide particles and imidazolium ionic liquid to form a second mixture; (2) reacting the second mixture at 160-240 DEG C to obtain a precursor; and (3) roasting the precursor at 600-1000 DEG C to obtain the silicon dioxide-cerium dioxide particles. According to the method disclosed by the invention, the silicon dioxide-cerium dioxide particles with good dispersity and specific particle size and morphology can be obtained.

Description

Technical Field

[0001] The present invention relates to a silica-ceria particle, a preparation method thereof, and the use of an ionic liquid. Background Art

[0002] Chemical mechanical polishing is a technique for providing global planarization in the manufacturing process of very large scale integrated circuits. Combining silica with ceria can affect the cerium content, thereby affecting the polishing efficiency. In addition, silica is also an excellent polishing abrasive, which has a "repair" effect on the scratches generated by ceria polishing, equivalent to "two" polishings. Therefore, the development of silica-ceria composites is one of the research hotspots of current polishing abrasives.

[0003] Traditional methods for preparing silica-ceria composites mainly include hydrothermal, sol-gel, co-precipitation, impregnation, filtration, and high-temperature calcination methods, etc., but they all have defects such as long preparation cycles, complex preparation methods, easy agglomeration of particles, and uneven size and shape.

[0004] Ionic liquid is a new type of green solvent, an ionic compound composed of anions and cations, also known as an organic salt. Due to its special chemical and physical properties, such as a wide liquid range with a melting point near room temperature, good stability in air and moisture, high solubility, low vapor pressure, low toxicity, non-flammability, and a wide potential window, etc., it has received extensive attention. Ionic liquids can be used as solvents, reactants, and templates for manufacturing inorganic materials. Summary of the Invention

[0005] One object of the present invention is to provide a preparation method of silica-ceria particles, which can obtain silica-ceria particles with good dispersibility, specific particle size and morphology. Further, the silica-ceria particles obtained by the preparation method of the present invention have high crystallinity, regular morphology, and uniform dispersion. Another object of the present invention is to provide a silica-ceria particle. Still another object of the present invention is to provide the use of an ionic liquid.

[0006] The present invention realizes the above objects through the following technical solutions.

[0007] On the one hand, the present invention provides a preparation method of silica-ceria particles, comprising the following steps:

[0008] (1) Adding an aqueous cerium salt solution to a first mixture containing silica particles and an ionic liquid to form a second mixture;

[0009] (2) Reacting the second mixture at 160-240 °C to obtain a precursor;

[0010] (3) The precursor is calcined at 600 - 1000 °C to obtain silica - cerium dioxide particles;

[0011] The cation of the ionic liquid is as shown in formula (I):

[0012]

[0013] Wherein, R1 and R2 are each independently selected from C1 - C6 alkyl groups; R3 is selected from H, C1 - C6 alkyl groups;

[0014] The anion of the ionic liquid is selected from one or more of BF4 - , Cl - , Br - , NO3 - , PF6 - , H2PO4 - ;

[0015] In the second mixture, the molar mass ratio of cerium element to silica particles is 2:(150 - 300) mol / g.

[0016] The silica particles of the present invention are hydrophilic silica particles. The surface of the hydrophilic silica particles has abundant hydroxyl groups and is not modified with hydrophobic groups.

[0017] The silica particles of the present invention are in an amorphous form.

[0018] The particle size of the silica particles can be 50 - 500 nm; preferably 100 - 300 nm.

[0019] Preferably, in the second mixture, the molar mass ratio of cerium element to silica particles is 2:(170 - 250) mol / g; more preferably, in the second mixture, the molar mass ratio of cerium element to silica particles is 2:(180 - 200) mol / g.

[0020] According to the preparation method of the present invention, preferably, the mass - volume ratio of silica particles to ionic liquid is (150 - 300):30 mg / mL.

[0021] Preferably, the mass - volume ratio of silica particles to ionic liquid is (170 - 250):30 mg / mL. More preferably, the mass - volume ratio of silica particles to ionic liquid is (180 - 200):30 mg / mL.

[0022] According to the preparation method of the present invention, preferably, the cerium salt aqueous solution is selected from one or more of cerium nitrate aqueous solution, cerium chloride aqueous solution, cerium sulfate aqueous solution;

[0023] The concentration of the cerium salt solution is 0.1 to 10 mol / L.

[0024] The cerium salt solution can be an aqueous solution of an inorganic cerium salt. According to an embodiment of the present invention, the cerium salt solution is an aqueous solution of cerium nitrate. Cerium nitrate can be used in the form of its hydrate. For example, cerium nitrate hexahydrate.

[0025] Preferably, the concentration of the cerium salt solution is 0.3 to 5 mol / L; more preferably, the concentration of the cerium salt solution is 0.5 to 1 mol / L.

[0026] According to the preparation method of the present invention, preferably, in the second mixture, the volume ratio of the ionic liquid to water is 30:(1 to 7).

[0027] Preferably, in the second mixture, the volume ratio of the ionic liquid to water is 30:(2 to 6); more preferably, in the second mixture, the volume ratio of the ionic liquid to water is 30:(3 to 5).

[0028] According to the preparation method of the present invention, preferably, R1 and R2 are each independently selected from C1-C3 alkyl groups, and R3 is H;

[0029] The anion of the ionic liquid is BF4 - .

[0030] Preferably, the alkyl group is a straight-chain alkyl group; more preferably, the alkyl group is a linear alkyl group. Examples of the alkyl group include, but are not limited to, methyl, ethyl, propyl, butyl, pentyl, and hexyl.

[0031] According to an embodiment of the present invention, the ionic liquid is 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0032] The above ionic liquid helps to form silica-cerium dioxide particles with a specific particle size and shape, improving the dispersibility.

[0033] According to the preparation method of the present invention, preferably, in step (2), the reaction time is 10 to 30 h; in step (3), the calcination time is 1 to 3 h.

[0034] In step (2), the reaction temperature is preferably 180 to 220 °C; more preferably 190 to 210 °C.

[0035] Preferably, in step (2), the reaction time is 15 to 25 h; more preferably, in step (2), the reaction time is 16 to 20 h.

[0036] In step (3), the calcination temperature is preferably 700 to 900 °C; more preferably 700 to 800 °C.

[0037] In step (3), the calcination time is preferably 2 to 2.5 h.

[0038] The second mixture can be reacted in a polytetrafluoroethylene reactor.

[0039] In certain embodiments, the following steps are further included: solid-liquid separating the reaction product obtained from the reaction to obtain a solid product. Washing the solid product and then drying it to obtain a precursor.

[0040] The reaction product can be solid-liquid separated by centrifugation or filtration. Preferably, centrifugation is used. Before solid-liquid separation, the reaction product can be first cooled to 20-35°C; preferably, cooled to 25-30°C.

[0041] The purpose of washing is to wash away the impurities attached to the solid product. The washing method is not limited herein, and conventional methods in the art can be used. The detergent used for washing can be selected from monohydric alcohols containing 1-6 carbon atoms. For example, methanol, ethanol, propanol, isopropanol.

[0042] The purpose of drying is to remove the liquid attached to the surface of the washed solid product. Preferably, the drying temperature is 60-95°C; more preferably 75-85°C. Preferably, the drying time is 7-15 h; preferably 9-12 h. Drying can be carried out in an oven.

[0043] Calcination can be carried out in a muffle furnace.

[0044] In certain embodiments, the following steps are further included: after cooling the calcined product, grinding it to obtain silica-ceria particles.

[0045] Grinding disperses some of the particles that are adhered or agglomerated together, and does not change the shape and particle size of the particles.

[0046] The method of the present invention can obtain silica-ceria particles with small particle size, narrow particle size distribution range, and controllable morphology without using air flow pulverization and precision classification.

[0047] After the cerium salt aqueous solution is added to the first mixture, it is stirred at 20-35°C; preferably, 25-30°C for 10-60 min; preferably, 20-40 min to obtain a second mixture.

[0048] On the other hand, the present invention provides a silica-ceria particle, which is prepared by the above preparation method;

[0049] The particle size range of the silica-ceria particles is 100-400 nm. In certain embodiments, the particle size range is 100-300 nm.

[0050] The silica-cerium dioxide particles of the present invention are spherical, spheroid-like or shower flower-like.

[0051] In the silica-cerium dioxide particles of the present invention, the silica is in an amorphous form. The obtained silica-cerium dioxide particles are a silicon-cerium composite product.

[0052] On the other hand, the present invention provides a use of an ionic liquid in regulating the particle size and / or morphology of silica-cerium dioxide particles, and the cation of the ionic liquid is as shown in formula (I):

[0053]

[0054] wherein, R1 and R2 are each independently selected from C1-C6 alkyl groups; R3 is selected from H, C1-C6 alkyl groups;

[0055] The anion of the ionic liquid is selected from BF4 - , Cl - , Br - , NO3 - , PF6 - , H2PO4 - or one or more of them.

[0056] According to the use of the present invention, preferably, it includes the following steps:

[0057] (1) Adding an aqueous solution of cerium salt to a first mixture containing silica particles and an ionic liquid to form a second mixture;

[0058] (2) Reacting the second mixture at 160-240 °C to obtain a precursor;

[0059] (3) Calcining the precursor at 600-1000 °C to obtain silica-cerium dioxide particles.

[0060] The selection of the ionic liquid and the specific steps and parameters are as described above, and will not be elaborated here.

[0061] The preparation method of the present invention can obtain silica-cerium dioxide particles with good dispersibility and a particle size of 100-400 nm. The silica-cerium dioxide particles of the present invention are spherical or shower flower-like. The silica-cerium dioxide particles of the present invention have a high crystallinity and regular morphology. The preparation method of the present invention does not require the use of a surfactant or a dispersant during the preparation process. Description of the Drawings

[0062] Figure 1 SEM image of the silica-cerium dioxide particles obtained in Example 1.

[0063] Figure 2XRD patterns of the silica-ceria particles, silica particles, and ceria obtained in Example 1.

[0064] Figure 3 EDS pattern of the silica-ceria particles obtained in Example 1.

[0065] Figure 4 SEM image of the silica-ceria particles obtained in Comparative Example 1. Detailed implementation manners

[0066] The present invention will be further described below in conjunction with specific embodiments, but the protection scope of the present invention is not limited thereto.

[0067] The following introduces the test methods:

[0068] XRD: Test was carried out using an X'Pert PRO X-ray diffractometer.

[0069] SEM, EDS: Tests were carried out using a ZEISS Sigma 500 field emission scanning electron microscope.

[0070] The following introduces the raw materials:

[0071] Hydrophilic silica particles: with a particle size of 100 - 300 nm, purchased from Shanghai Macklin Biochemical Co., Ltd.

[0072] Example 1

[0073] Add 0.19 g of hydrophilic silica particles to 30 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, and stir at 25°C for 30 min to obtain a first mixture.

[0074] Mix cerium nitrate hexahydrate and water to obtain a cerium salt aqueous solution with a concentration of 0.5 mol / L.

[0075] Add 4 mL of the cerium salt aqueous solution to the first mixture, and stir at 25°C for 30 min to obtain a second mixture.

[0076] Place the second mixture in a polytetrafluoroethylene reaction kettle, react at 210°C for 16 h; cool the reaction product to 25°C, then centrifuge to separate the solid product. Wash the solid product three times with absolute ethanol; dry the washed solid product in an oven at 80°C for 10 h to obtain a precursor.

[0077] Calcine the precursor in a muffle furnace at 700°C for 2 h to obtain a calcined product. Cool the calcined product and grind it to obtain silica-ceria particles.

[0078] Figure 1 SEM image of the silica-ceria particles obtained in Example 1. From Figure 1 it can be seen that the silica-ceria particles obtained in this example are spherical or flower-like, with small balls attached to large balls, and their particle size is 100 - 300 nm, and the particle size distribution is narrow. The silica-ceria particles in this example have good crystallinity, regular morphology, uniform dispersion, and good dispersibility.

[0079] Figure 2 XRD patterns of the silica-ceria particles, silica particles (raw materials), and ceria obtained in Example 1. From Figure 2 it can be seen that silica is in an amorphous structure and has an obvious diffraction peak at 23°. According to the XRD standard card of CeO2, the peaks of CeO2 at 2θ = 28.5°, 33.0°, 47.4°, 56.3°, 59.1°, 69.4°, 76.7°, 79.1°, and 88.4° correspond to the (111), (200), (220), (311), (222), (400), (331), (420), and (422) crystal planes. The results show that no silica peak was detected in the silica-ceria particles, and silica exists in an amorphous form.

[0080] Figure 3 EDS image of the silica-ceria particles obtained in Example 1. According to the ESD elemental analysis, the silica-ceria particles are composed of silicon, cerium, and oxygen elements. The atomic content of silicon element is 44.46%, the atomic content of cerium element is 28.08%, and the atomic content of oxygen element is 27.46%.

[0081] Example 2

[0082] 0.217 g of hydrophilic silica particles were added to 30 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid, and stirred at 25 °C for 30 min to obtain a first mixture.

[0083] Cerium nitrate hexahydrate and water were mixed to obtain a cerium salt aqueous solution with a concentration of 0.5 mol / L.

[0084] 4 mL of the cerium salt aqueous solution was added to the first mixture, and stirred at 25 °C for 30 min to obtain a second mixture.

[0085] The second mixture was placed in a polytetrafluoroethylene reaction kettle and reacted at 180 °C for 16 h; the reaction product was cooled to 25 °C, then centrifuged to separate the solid product. The solid product was washed three times with anhydrous ethanol; the washed solid product was dried in an oven at 80 °C for 10 h to obtain a precursor.

[0086] The precursor was calcined in a muffle furnace at 700° C. for 2 hours to obtain a calcined product. The calcined product was cooled and ground to obtain silica-ceria particles.

[0087] The obtained silica-ceria particles have a particle size of 100 to 400 nm and are spherical or bath-flower-like in shape.

[0088] Comparative Example 1

[0089] 0.434 g of hydrophilic silica particles was added to 30 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate ionic liquid and stirred at 25° C. for 30 min to obtain a first mixture.

[0090] Cerium nitrate hexahydrate and water were mixed to obtain a cerium salt aqueous solution with a concentration of 0.5 mol / L.

[0091] 4 mL of the cerium salt aqueous solution was added to the first mixture, and stirred at 25° C. for 30 min to obtain a second mixture.

[0092] The second mixture was placed in a polytetrafluoroethylene reactor and reacted at 240°C for 10 hours; the reaction product was cooled to 25°C and then centrifuged to separate the solid product. The solid product was washed three times with anhydrous ethanol; the washed solid product was dried in an oven at 80°C for 10 hours to obtain a precursor.

[0093] The precursor was calcined in a muffle furnace at 600° C. for 2 h to obtain a calcined product. The calcined product was cooled and ground to obtain silica-ceria particles.

[0094] Figure 4 is a SEM image of the silica-cerium dioxide particles obtained in this comparative example. Figure 4 It can be seen that the size of the silica-cerium dioxide particles in this comparative example is between 50 and 500 nm, the particle size is uneven, and the dispersion is relatively large. The morphology of the particles is quite different, including spherical, bath flower-shaped, curved, irregular and other morphologies.

[0095] The present invention is not limited to the above-mentioned embodiments. Without departing from the essential content of the present invention, any deformation, improvement and substitution that can be conceived by those skilled in the art shall fall within the scope of the present invention.

Claims

1. A method for preparing silicon dioxide-cerium dioxide particles, characterized in that: The steps include: (1) adding an aqueous cerium salt solution to a first mixture containing silica particles and an ionic liquid to form a second mixture; (2) reacting the second mixture at 160-240° C. to obtain a precursor; (3) calcining the precursor at 600-1000° C. to obtain silica-ceria particles; The cation of the ionic liquid is shown in formula (I): Wherein, R1 and R2 are independently selected from C1-C6 alkyl groups; R3 is selected from H, C1-C6 alkyl groups; The anion of the ionic liquid is selected from BF4 - , Cl - Br - 、NO3 - PF6 - 、H2PO4 - One or more of; In the second mixture, the molar mass ratio of the cerium element to the silicon dioxide particles is 2:(150-300) mol / g.

2. The preparation method according to claim 1, characterized in that: The mass volume ratio of silica particles and ionic liquid is (150-300):30 mg / mL.

3. The preparation method according to claim 1, characterized in that: The cerium salt aqueous solution is selected from one or more of a cerium nitrate aqueous solution, a cerium chloride aqueous solution, and a cerium sulfate aqueous solution; The concentration of the cerium salt aqueous solution is 0.1-10 mol / L.

4. The preparation method according to claim 1, characterized in that: In the second mixture, the volume ratio of the ionic liquid to water is 30:(1-7).

5. The preparation method according to claim 1, characterized in that: R1 and R2 are independently selected from C1-C3 alkyl groups, and R3 is H; The anion of the ionic liquid is BF4 - .

6. The preparation method according to claim 1, characterized in that: In step (2), the reaction time is 10 to 30 hours; in step (3), the calcination time is 1 to 3 hours.

7. The preparation method according to any one of claims 1 to 6, characterized in that: Step (2) is carried out in the absence of a surfactant and / or a dispersant.

8. A silica-ceria particle, characterized in that: The silica-cerium dioxide particles are prepared by the preparation method according to any one of claims 1 to 7; The particle size of the silicon dioxide-cerium dioxide particles ranges from 100 to 400 nm.

9. Use of an ionic liquid in regulating the particle size and / or morphology of silica-ceria particles, characterized in that: The cation of the ionic liquid is shown in formula (I): Wherein, R1 and R2 are independently selected from C1-C6 alkyl groups; R3 is selected from H, C1-C6 alkyl groups; The anion of the ionic liquid is selected from BF4 - , Cl - Br - 、NO3 - PF6 - 、H2PO4 - One or more of .

10. The use according to claim 9, characterized in that The steps include: (1) adding an aqueous cerium salt solution to a first mixture containing silica particles and an ionic liquid to form a second mixture; (2) reacting the second mixture at 160-240° C. to obtain a precursor; (3) calcining the precursor at 600-1000° C. to obtain silica-ceria particles.

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